Letter to the Editor

The XMM-Ω project

II. Cosmological implications from the high redshift L – T relation of X-ray clusters

¹ Laboratoire d'astrophysique de l'observatoire Midi-Pyrénées, CNRS, UMR 5572, UPS, 14 Av. E. Belin, 31400 Toulouse, France
² APC, Université Denis Diderot, Paris VII, 75005 Paris, France
³ 
Observatoire astronomique de Strasbourg, CDS, ULP, 11 rue de l'université, 67000 Strasbourg, France
⁴ Centre d'étude spatiale des rayonnements, OMP, UPS, 9, Av. du Colonel Roche, BP 4346, 31028 Toulouse, France
⁵ 
Advanced Concepts and Science Payloads Office, European Space Agency, ESTEC, 2200AG Noordwijk, The Netherlands
⁶ Institut d'astrophysique spatiale, Université Paris-sud, 91405 Orsay Cedex, France
⁷ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA02138, USA

Corresponding author: A. Blanchard, alain.blanchard@ast.obs-mip.fr

Received: 15 August 2003
Accepted: 5 November 2003

Abstract

The evolution with redshift of the temperature-luminosity relation of X-ray galaxy clusters is a key ingredient to break degeneracies in the interpretation of X-ray clusters redshift number counts. We therefore take advantage of the recent measurements of the temperature-luminosity relation of distant clusters observed with XMM-Newton and Chandra satellites to examine theoretical number counts expected for different available X-rays cluster samples, namely the RDCS, EMSS, SHARC, 160 deg² and the MACS at redshift greater than 0.3. We derive these counts without any adjustment, using models previously normalized to the local () temperature distribution function (TDF) and to the high-z () TDF. We find that these models having in the range [0.85–1.] predict counts in remarkable agreement with the observed counts in the different samples. We illustrate that this conclusion is weakly sensitive to the various ingredients of the modeling. Therefore number counts provide a robust evidence of an evolving population. A realistic flat low density model (), normalized to the local abundance of clusters is found to overproduce cluster abundance at high redshift (above ) by nearly an order of magnitude. This result is in conflict with the popular concordance model. The conflict could indicate a deviation from the expected scaling of the relation with redshift.